Parvovirus B19 (B19V) causes erythema infectiosum, a.k.a., fifth disease. This disease primarily affects children. It is generally self-limiting and subsides after 1-2 weeks. In pregnancy, the virus can cross the placenta and result in a fetal infection. This may lead to severe fetal anemia, hydrops fetalis, a miscarriage, or intrauterine fetal death. The risk of long-term sequelae also appears to be increased. About one-third of pregnant women are not immune to B19V and, therefore, are at risk to contract a primary infection. The seroconversion rate during pregnancy is generally around 1-2%. During a primary infection, maternal-fetal transplacental transmission of B19V occurs in about 30-50% of the cases and the risk of fetal infection increases with advancing gestational age. The risk of severe fetal anemia or hydrops is around 3-4% overall and is around 6-7% if the primary infection occurs before 20 weeks' gestation. Fetal monitoring in women with a primary B19V infection includes regular ultrasound examinations looking for evidence of hydrops fetalis and Doppler measurements of the middle cerebral artery peak velocity. Fetal blood sampling is performed if a significant anemia is suspected and, if such is found, an intrauterine blood transfusion is needed. This article provides an overview of the epidemiology, pathogenesis, clinical manifestations, diagnostic methods, and management of B19V infection during pregnancy.

Childcare providers are overwhelmingly women of childbearing age. Occupational risks in this sector include exposure to biological (infectious) or physical (standing, carrying loads) hazards, many of which are associated with adverse pregnancy outcomes such as children with congenital infections, low birth weight or prematurity. Here, the authors examined literature on pregnancy outcomes and infectious hazards related to employment in daycare settings. Overall, 33 original studies (10 reporting pregnancy issues, 23 focusing on infectious risks) published in 1980-2018 were retained following a Medline search. Pregnancy issues in daycare workers have rarely been studied, and inconsistent risks of spontaneous abortion, congenital malformations and fetal growth retardation have been reported. Literature pertaining to infectious risks in daycare settings is extensive. The risk of a primary cytomegalovirus infection during pregnancy was increased for daycare workers caring for >6 children and younger children, changing diapers ≥3 days/week, not wearing gloves when changing diapers, and having employment in daycare for ≤2 years. Personal factors (nulliparity, ethnicity) were also independent risk factors. Parvovirus B19 (B19V) infections appear to be related to employment in daycare, but also to having one's own children and an increased number of siblings. Consequently, the risk of a primary B19V infection during an outbreak is of most concern among younger nulliparous workers caring for large numbers of young infected children. Since the main occupational hazard is viral infection, feasible prevention strategies include improving workers' awareness, serological monitoring during pregnancy, educating on appropriate preventive measures, and ensuring age-appropriate immunization of children and staff in childcare facilities. Int J Occup Med Environ Health. 2020;33(6):733-56.

Infection with parvovirus B19 (B19V) during pregnancy may cause severe fetal anemia, hydrops, and fe tal death. Furthermore, neurodevelopmental impairment among survivors may occur despite appropriate prenatal management, including intrauterine transfusion (IUT). Our primary objective was to describe cerebral lesions on MRI in fetuses with severe anemia requiring IUT for B19V infection. Our secondary objective was to search for clinical and biological characteristics associated with the occurrence of such lesions. We performed a retrospective review of data on fetuses infected with B19V and requiring at least one IUT between 2005 and 2016. Fetuses with abnormal cerebral MRI results in the 3rd trimester were compared to those with normal MRI results. Of 34 transfused fetuses, 26 children were born at full term. Five intrauterine fetal deaths, 1 neonatal death, and 2 terminations of pregnancy occurred. Cerebral anomalies were observed in 7/27 fetuses on MRI, including cerebellar hemorrhage or a small cerebellum. Only viral load in fetal blood appeared to be associated with brain lesions (11.5 log10 copies/mL [10.5-12.5] in case of abnormal MRI results vs. 9.5 log10 copies/mL [7.8-10.0]; p = 0.05). Among the fetuses transfused for B19V infection, 26% presented with prenatal abnormal cerebral imaging results. In our study, viral load in fetal blood appeared to be the only factor associated with fetal brain lesions.

Common causes of fetal anemia and hydrops include parvovirus B19 infection during the first 2 trimesters of pregnancy, as well as maternal alloimmunization to RhD with subsequent hemolytic disease of the fetus and newborn (HDFN) in an RhD positive fetus. Although both of these conditions have historically caused significant fetal morbidity and mortality, the advent of intrauterine transfusion (IUT) over the last few decades has dramatically improved outcomes. Prior literature has extensively documented placental changes associated with untreated parvovirus infection and RhD HDFN in intrauterine fetal demises and preterm births; however, histopathologic changes in term placentas from term infants treated with IUT have not been reported. We present placental findings in 2 cases of parvovirus B19-associated hydrops and 2 cases of RhD HDFN-associated hydrops in term infants after IUT, highlighting unique aspects that may be diagnostically useful for the examining pathologist.

Some childhood acute lymphoblastic leukaemias (ALL) can be traced back to a prenatal origin, where a virus infection could be involved in the first pre-leukaemic clone development. The DNA virome of 95 children who later developed ALL was characterised from neonatal blood spots (NBS) using unbiased next-generation sequencing (NGS) and compared with the virome of 95 non-ALL controls. DNA was individually extracted from the ALL-patients and controls, pooled, randomly amplified and sequenced using the Illumina MiSeq Sequencing System. Virus-like sequences identified in both groups mapped to human endogenous retroviruses and propionibacterium phage, considered a part of the normal microbial flora. Potential pathogens human herpesvirus type 6 (HHV-6) and parvovirus B19 were also identified, but only few samples in both ALL and controls tested positive by PCR follow-up. Unbiased NGS was employed to search for DNA from potential infectious agents in neonatal samples of children who later developed ALL. Although several viral candidates were identified in the NBS samples, further investigation by PCR suggested that these viruses did not have a major role in ALL development.